1. Field of the Invention
The field of art to which this invention pertains is solid-bed adsorptive separation. More specifically, the invention relates to an improved adsorbent, method of manufacture of the adsorbent and improved process for separating a component from a mixture comprising an aqueous solution of a mixture of different components which process employs an adsorbent comprising a crystalline aluminosilicate which selectively adsorbs a component from the feed mixture.
2. PRIOR ART
It is known in the separation art that certain crystalline aluminosilicates referred to as zeolites can be used in the separation of a component from an aqueous solution of a mixture of different components. For example, adsorbents comprising crystalline aluminosilicates are used in the method described in U.S. Pat. No. 4,014,711 to separate fructose from a mixture of sugars in aqueous solution including fructose and glucose.
It is also known that crystalline aluminosilicates or zeolites are used in adsorption processing in the form of aggolomerates having high physical strength and attrition resistance. Methods for forming the crystalline powders into such aggolomerates include the addition of an inorganic binder, generally a clay comprising silicon dioxide and aluminum oxide to the high purity zeolite powder in wet mixture. The blended clay zeolite mixture is extruded into cylindrical type pellets or formed into beads which are subsequently calcined in order to convert the clay to an amorphous binder of considerable mechanical strength. As binders, clays of the kaolin type are generally used.
Zeolite crystal and inorganic binder agglomerates have long been known to have the property of gradually disintegrating as a result of continuous contact with water. This disintegration has been observed as a silicon presence or contamination in the solution in contact with the adsorbent. Such contamination may at times be sufficiently severe to impart a cloudy appearance to the solution.
U.S. Pat. No. 3,262,890 discloses the use of cellulose acetate bonded zeolite particles as a desiccant for a refrigerant, such as a halogenated fluorocarbon, in a refrigeration system.
U.S. Pat. No. 3,951,859 discloses molecular sieving particles comprising adsorbent powders dispersed in a matrix of microporous polymer gels such as cellulose esters. The preparation shown includes the use of different organic solvents for the cellulose esters. Zeolites are not mentioned as possible adsorbent powders and the manufacture of the particles requires an emulsification step in which the adsorbent particle polymer solvent mixture is emulsified in an aqueous solution.
I have discovered an improvement to an aqueous separation process in which a zeolite containing adsorbent is used which minimizes the disintegration of the adsorbent and silicon contamination of the product.